This invention relates to the catching of ink at an ink jet orifice during the priming and/or purging of an ink prior to ink jet printing.
In ink jet printing applications, it is necessary to prime an ink jet with ink prior to initiating printing so as to assure that ink is available at the orifice of an ink jet when required. Typically, this involves the introduction of a substantial amount of ink into an ink jet which necessarily produces a collection of ink at the ink jet orifice which must be removed prior to initiating printing. If the collection of ink, which may resemble a glob at the orifice of the ink jet, is not removed prior to printing, it is not possible to precisely project droplets of ink with the appropriate resolution and direction for ink jet printing. It will, of course, be appreciated that the evaporation of this collection of ink at the orifice could actually produce a blockage of the ink jet.
A similar requirement for removal of ink which collects at the orifice of an ink jet occurs during the purging of an ink jet. Purging occurs when it is desirable to clean the ink jet and remove all debris including the residue of evaporated ink. During purging, a substantial amount of ink is passed through the ink jet with a resulting collection at the ink jet orifice. This ink must also be removed prior to printing for the reasons discussed above.
Heretofore, various techniques have been utilized to remove the collection of ink which occurs as a result of priming and/or purging. One technique involves the mechanical wiping of the ink jet tip. Other techniques involve the use of a charging ring or rod, positioned near the tip of the jet, which relies upon gravity and the wetting action of the ink or printing fluid to remove the collection of ink at the ink jet orifice which occurs during priming or purging.
U.S. Pat. No. 4,123,761--Kimura et al. discloses the use of a suction tube which is movable into a position adjacent an ink jet orifice for purposes of removing ink emerging from the orifice of the ink jet during purging. The suction tube, which does not form part of a chamber surrounding the orifice, is substantially axially aligned with the ink jet orifice during purging.
U.S. Pat. No. 3,972,051--Lundquist et al. discloses the use of air suction adjacent an ink jet orifice. However, the air suction is not utilized nor is it operable with respect to the ink to remove ink. Rather, the purpose of the air suction is to prevent air build-up at the document interface and to maintain laminarity at the document interface.
U.S. Pat. Nos. 3,936,135--Duffield and 4,023,182--Arway et al. disclose the use of vacuum catchers communicating with the orifice of an ink jet. However, the purpose of these catchers is to collect ink jet droplets which are projected from the orifice as contrasted with the collection of ink at the orifice. For this reason, the ink jet catchers are spaced from and do not form part of a catcher chamber at the ink jet orifice. Swiss Pat. No. 581,025 discloses a similar catcher arrangement for projected droplets of ink.